/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package core.net;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.NetworkInterface;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketException;
import java.net.URI;
import java.net.UnknownHostException;
import java.nio.channels.SocketChannel;
import java.util.Map.Entry;
import java.util.*;

import javax.net.SocketFactory;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.ipc.Server;
import org.apache.hadoop.ipc.VersionedProtocol;
import org.apache.hadoop.util.ReflectionUtils;

public class NetUtils {
	private static final Log LOG = LogFactory.getLog(NetUtils.class);

	private static Map<String, String> hostToResolved = new HashMap<String, String>();

	/**
	 * Get the socket factory for the given class according to its configuration
	 * parameter <tt>hadoop.rpc.socket.factory.class.&lt;ClassName&gt;</tt>.
	 * When no such parameter exists then fall back on the default socket
	 * factory as configured by <tt>hadoop.rpc.socket.factory.class.default</tt>
	 * . If this default socket factory is not configured, then fall back on the
	 * JVM default socket factory.
	 * 
	 * @param conf
	 *            the configuration
	 * @param clazz
	 *            the class (usually a {@link VersionedProtocol})
	 * @return a socket factory
	 */
	public static SocketFactory getSocketFactory(Configuration conf,
			Class<?> clazz) {

		SocketFactory factory = null;

		String propValue = conf.get("hadoop.rpc.socket.factory.class."
				+ clazz.getSimpleName());
		if ((propValue != null) && (propValue.length() > 0))
			factory = getSocketFactoryFromProperty(conf, propValue);

		if (factory == null)
			factory = getDefaultSocketFactory(conf);

		return factory;
	}

	/**
	 * Get the default socket factory as specified by the configuration
	 * parameter <tt>hadoop.rpc.socket.factory.default</tt>
	 * 
	 * @param conf
	 *            the configuration
	 * @return the default socket factory as specified in the configuration or
	 *         the JVM default socket factory if the configuration does not
	 *         contain a default socket factory property.
	 */
	public static SocketFactory getDefaultSocketFactory(Configuration conf) {

		String propValue = conf.get("hadoop.rpc.socket.factory.class.default");
		if ((propValue == null) || (propValue.length() == 0))
			return SocketFactory.getDefault();

		return getSocketFactoryFromProperty(conf, propValue);
	}

	/**
	 * Get the socket factory corresponding to the given proxy URI. If the given
	 * proxy URI corresponds to an absence of configuration parameter, returns
	 * null. If the URI is malformed raises an exception.
	 * 
	 * @param propValue
	 *            the property which is the class name of the SocketFactory to
	 *            instantiate; assumed non null and non empty.
	 * @return a socket factory as defined in the property value.
	 */
	public static SocketFactory getSocketFactoryFromProperty(
			Configuration conf, String propValue) {

		try {
			Class<?> theClass = conf.getClassByName(propValue);
			return (SocketFactory) ReflectionUtils.newInstance(theClass, conf);

		} catch (ClassNotFoundException cnfe) {
			throw new RuntimeException("Socket Factory class not found: "
					+ cnfe);
		}
	}

	/**
	 * Util method to build socket addr from either: <host>:<post>
	 * <fs>://<host>:<port>/<path>
	 */
	public static InetSocketAddress createSocketAddr(String target) {
		return createSocketAddr(target, -1);
	}

	/**
	 * Util method to build socket addr from either: <host> <host>:<post>
	 * <fs>://<host>:<port>/<path>
	 */
	public static InetSocketAddress createSocketAddr(String target,
			int defaultPort) {
		int colonIndex = target.indexOf(':');
		if (colonIndex < 0 && defaultPort == -1) {
			throw new RuntimeException("Not a host:port pair: " + target);
		}
		String hostname;
		int port = -1;
		if (!target.contains("/")) {
			if (colonIndex == -1) {
				hostname = target;
			} else {
				// must be the old style <host>:<port>
				hostname = target.substring(0, colonIndex);
				port = Integer.parseInt(target.substring(colonIndex + 1));
			}
		} else {
			// a new uri
			URI addr = new Path(target).toUri();
			hostname = addr.getHost();
			port = addr.getPort();
		}

		if (port == -1) {
			port = defaultPort;
		}

		if (getStaticResolution(hostname) != null) {
			hostname = getStaticResolution(hostname);
		}
		return new InetSocketAddress(hostname, port);
	}

	/**
	 * Handle the transition from pairs of attributes specifying a host and port
	 * to a single colon separated one.
	 * 
	 * @param conf
	 *            the configuration to check
	 * @param oldBindAddressName
	 *            the old address attribute name
	 * @param oldPortName
	 *            the old port attribute name
	 * @param newBindAddressName
	 *            the new combined name
	 * @return the complete address from the configuration
	 */
	@Deprecated
	public static String getServerAddress(Configuration conf,
			String oldBindAddressName, String oldPortName,
			String newBindAddressName) {
		String oldAddr = conf.get(oldBindAddressName);
		String oldPort = conf.get(oldPortName);
		String newAddrPort = conf.get(newBindAddressName);
		if (oldAddr == null && oldPort == null) {
			return newAddrPort;
		}
		String[] newAddrPortParts = newAddrPort.split(":", 2);
		if (newAddrPortParts.length != 2) {
			throw new IllegalArgumentException("Invalid address/port: "
					+ newAddrPort);
		}
		if (oldAddr == null) {
			oldAddr = newAddrPortParts[0];
		} else {
			LOG.warn("Configuration parameter " + oldBindAddressName
					+ " is deprecated. Use " + newBindAddressName + " instead.");
		}
		if (oldPort == null) {
			oldPort = newAddrPortParts[1];
		} else {
			LOG.warn("Configuration parameter " + oldPortName
					+ " is deprecated. Use " + newBindAddressName + " instead.");
		}
		return oldAddr + ":" + oldPort;
	}

	/**
	 * Adds a static resolution for host. This can be used for setting up
	 * hostnames with names that are fake to point to a well known host. For
	 * e.g. in some testcases we require to have daemons with different
	 * hostnames running on the same machine. In order to create connections to
	 * these daemons, one can set up mappings from those hostnames to
	 * "localhost". {@link NetUtils#getStaticResolution(String)} can be used to
	 * query for the actual hostname.
	 * 
	 * @param host
	 * @param resolvedName
	 */
	public static void addStaticResolution(String host, String resolvedName) {
		synchronized (hostToResolved) {
			hostToResolved.put(host, resolvedName);
		}
	}

	/**
	 * Retrieves the resolved name for the passed host. The resolved name must
	 * have been set earlier using
	 * {@link NetUtils#addStaticResolution(String, String)}
	 * 
	 * @param host
	 * @return the resolution
	 */
	public static String getStaticResolution(String host) {
		synchronized (hostToResolved) {
			return hostToResolved.get(host);
		}
	}

	/**
	 * This is used to get all the resolutions that were added using
	 * {@link NetUtils#addStaticResolution(String, String)}. The return value is
	 * a List each element of which contains an array of String of the form
	 * String[0]=hostname, String[1]=resolved-hostname
	 * 
	 * @return the list of resolutions
	 */
	public static List<String[]> getAllStaticResolutions() {
		synchronized (hostToResolved) {
			Set<Entry<String, String>> entries = hostToResolved.entrySet();
			if (entries.size() == 0) {
				return null;
			}
			List<String[]> l = new ArrayList<String[]>(entries.size());
			for (Entry<String, String> e : entries) {
				l.add(new String[] { e.getKey(), e.getValue() });
			}
			return l;
		}
	}

	/**
	 * Returns InetSocketAddress that a client can use to connect to the server.
	 * Server.getListenerAddress() is not correct when the server binds to
	 * "0.0.0.0". This returns "127.0.0.1:port" when the getListenerAddress()
	 * returns "0.0.0.0:port".
	 * 
	 * @param server
	 * @return socket address that a client can use to connect to the server.
	 */
	public static InetSocketAddress getConnectAddress(Server server) {
		InetSocketAddress addr = server.getListenerAddress();
		if (addr.getAddress().getHostAddress().equals("0.0.0.0")) {
			addr = new InetSocketAddress("127.0.0.1", addr.getPort());
		}
		return addr;
	}

	/**
	 * Same as getInputStream(socket, socket.getSoTimeout()).<br>
	 * <br>
	 * 
	 * From documentation for {@link #getInputStream(Socket, long)}:<br>
	 * Returns InputStream for the socket. If the socket has an associated
	 * SocketChannel then it returns a {@link SocketInputStream} with the given
	 * timeout. If the socket does not have a channel,
	 * {@link Socket#getInputStream()} is returned. In the later case, the
	 * timeout argument is ignored and the timeout set with
	 * {@link Socket#setSoTimeout(int)} applies for reads.<br>
	 * <br>
	 * 
	 * Any socket created using socket factories returned by {@link NetUtils},
	 * must use this interface instead of {@link Socket#getInputStream()}.
	 * 
	 * @see #getInputStream(Socket, long)
	 * 
	 * @param socket
	 * @return InputStream for reading from the socket.
	 * @throws IOException
	 */
	public static InputStream getInputStream(Socket socket) throws IOException {
		return getInputStream(socket, socket.getSoTimeout());
	}

	/**
	 * Returns InputStream for the socket. If the socket has an associated
	 * SocketChannel then it returns a {@link SocketInputStream} with the given
	 * timeout. If the socket does not have a channel,
	 * {@link Socket#getInputStream()} is returned. In the later case, the
	 * timeout argument is ignored and the timeout set with
	 * {@link Socket#setSoTimeout(int)} applies for reads.<br>
	 * <br>
	 * 
	 * Any socket created using socket factories returned by {@link NetUtils},
	 * must use this interface instead of {@link Socket#getInputStream()}.
	 * 
	 * @see Socket#getChannel()
	 * 
	 * @param socket
	 * @param timeout
	 *            timeout in milliseconds. This may not always apply. zero for
	 *            waiting as long as necessary.
	 * @return InputStream for reading from the socket.
	 * @throws IOException
	 */
	public static InputStream getInputStream(Socket socket, long timeout)
			throws IOException {
		return (socket.getChannel() == null) ? socket.getInputStream()
				: new SocketInputStream(socket, timeout);
	}

	/**
	 * Same as getOutputStream(socket, 0). Timeout of zero implies write will
	 * wait until data is available.<br>
	 * <br>
	 * 
	 * From documentation for {@link #getOutputStream(Socket, long)} : <br>
	 * Returns OutputStream for the socket. If the socket has an associated
	 * SocketChannel then it returns a {@link SocketOutputStream} with the given
	 * timeout. If the socket does not have a channel,
	 * {@link Socket#getOutputStream()} is returned. In the later case, the
	 * timeout argument is ignored and the write will wait until data is
	 * available.<br>
	 * <br>
	 * 
	 * Any socket created using socket factories returned by {@link NetUtils},
	 * must use this interface instead of {@link Socket#getOutputStream()}.
	 * 
	 * @see #getOutputStream(Socket, long)
	 * 
	 * @param socket
	 * @return OutputStream for writing to the socket.
	 * @throws IOException
	 */
	public static OutputStream getOutputStream(Socket socket)
			throws IOException {
		return getOutputStream(socket, 0);
	}

	/**
	 * Returns OutputStream for the socket. If the socket has an associated
	 * SocketChannel then it returns a {@link SocketOutputStream} with the given
	 * timeout. If the socket does not have a channel,
	 * {@link Socket#getOutputStream()} is returned. In the later case, the
	 * timeout argument is ignored and the write will wait until data is
	 * available.<br>
	 * <br>
	 * 
	 * Any socket created using socket factories returned by {@link NetUtils},
	 * must use this interface instead of {@link Socket#getOutputStream()}.
	 * 
	 * @see Socket#getChannel()
	 * 
	 * @param socket
	 * @param timeout
	 *            timeout in milliseconds. This may not always apply. zero for
	 *            waiting as long as necessary.
	 * @return OutputStream for writing to the socket.
	 * @throws IOException
	 */
	public static OutputStream getOutputStream(Socket socket, long timeout)
			throws IOException {
		return (socket.getChannel() == null) ? socket.getOutputStream()
				: new SocketOutputStream(socket, timeout);
	}

	/**
	 * This is a drop-in replacement for
	 * {@link Socket#connect(SocketAddress, int)}. In the case of normal sockets
	 * that don't have associated channels, this just invokes
	 * <code>socket.connect(endpoint, timeout)</code>. If
	 * <code>socket.getChannel()</code> returns a non-null channel, connect is
	 * implemented using Hadoop's selectors. This is done mainly to avoid Sun's
	 * connect implementation from creating thread-local selectors, since Hadoop
	 * does not have control on when these are closed and could end up taking
	 * all the available file descriptors.
	 * 
	 * @see java.net.Socket#connect(java.net.SocketAddress, int)
	 * 
	 * @param socket
	 * @param endpoint
	 * @param timeout
	 *            - timeout in milliseconds
	 */
	public static void connect(Socket socket, SocketAddress endpoint,
			int timeout) throws IOException {
		if (socket == null || endpoint == null || timeout < 0) {
			throw new IllegalArgumentException("Illegal argument for connect()");
		}

		SocketChannel ch = socket.getChannel();

		if (ch == null) {
			// let the default implementation handle it.
			socket.connect(endpoint, timeout);
		} else {
			SocketIOWithTimeout.connect(ch, endpoint, timeout);
		}
	}

	/**
	 * Given a string representation of a host, return its ip address in textual
	 * presentation.
	 * 
	 * @param name
	 *            a string representation of a host: either a textual
	 *            representation its IP address or its host name
	 * @return its IP address in the string format
	 */
	public static String normalizeHostName(String name) {
		if (Character.digit(name.charAt(0), 10) != -1) { // FIXME
			return name;
		} else {
			try {
				InetAddress ipAddress = InetAddress.getByName(name);
				return ipAddress.getHostAddress();
			} catch (UnknownHostException e) {
				return name;
			}
		}
	}

	/**
	 * Given a collection of string representation of hosts, return a list of
	 * corresponding IP addresses in the textual representation.
	 * 
	 * @param names
	 *            a collection of string representations of hosts
	 * @return a list of corresponding IP addresses in the string format
	 * @see #normalizeHostName(String)
	 */
	public static List<String> normalizeHostNames(Collection<String> names) {
		List<String> hostNames = new ArrayList<String>(names.size());
		for (String name : names) {
			hostNames.add(normalizeHostName(name));
		}
		return hostNames;
	}

	/**
	 * Checks if {@code host} is a local host name and return
	 * {@link InetAddress} corresponding to that address.
	 * 
	 * @param host
	 *            the specified host
	 * @return a valid local {@link InetAddress} or null
	 * @throws SocketException
	 *             if an I/O error occurs
	 */
	public static InetAddress getLocalInetAddress(String host)
			throws SocketException {
		if (host == null) {
			return null;
		}
		InetAddress addr = null;
		try {
			addr = InetAddress.getByName(host);
			if (NetworkInterface.getByInetAddress(addr) == null) {
				addr = null; // Not a local address
			}
		} catch (UnknownHostException ignore) {
		}
		return addr;
	}
}
